Led assembly with omnidirectional light field

ABSTRACT

Disclosed is an LED assembly having an omnidirectional light field. The LED assembly has a transparent substrate with first and second surfaces facing to opposite orientations respectively. LED chips are mounted on the first surface and are electrically interconnected by a circuit. A transparent capsule with a phosphor dispersed therein is formed on the first surface and substantially encloses the circuit and the LED chips. First and second electrode plates are formed on the first or second surface, and electrically connected to the LED chips.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of TaiwanApplication Series Number 102122873 filed on Jun. 27, 2013 and TaiwanApplication Series Number 103111887 filed on Mar. 27, 2014, which areincorporated by reference in their entirety.

BACKGROUND

The present disclosure relates generally to light emitting diode (LED)assemblies, and more specifically, to LED assembly that has anomnidirectional light field.

LED has been used in different kinds of appliances in our daily life,such as traffic lights, car headlights, street lamps, computerindicators, flashlights, LCD backlight modules, and so on. Beside thesemiconductor manufacturing process in the front end, the LED chips usedin these appliances should go through LED packaging in the back end.

LED packaging mainly provides mechanical, electrical, thermal, andoptical supports to LED chips. LED chips, which are a kind ofsemiconductor products, are prone to performance degradation, or aging,if exposed for a long time in an atmosphere full of humidity orchemical. Epoxy resin is commonly used in LED packaging to cover or sealLED chips, such that LED chips are effectively isolated from detrimentalatmosphere. Furthermore, LED packaging should take heat dissipation andluminance extraction into consideration, in order to make LED assemblymore power-saving and reliable. Heat generated in an LED chip must bedissipated efficiently. Otherwise, heat accumulated in the PN junctionof an LED chip will damage or degrade its performance, shortening itslifespan. Optical design is also a key factor when designing of LEDpackaging. Light emitted from an LED chip must be transmitted in a waythat results in certain luminance distribution with certain intensity.

The design for packaging a white LED further needs to consider colortemperature, color rendering index, phosphor, etc. The white LED couldbe provided by phosphor converting a portion of blue light from a blueLED chip into green/yellow light such that the mixture of the lights isperceived as white light by human eyes. Because human eyes arevulnerable to high-intensity blue light, the blue light from a blue LEDchip in a white LED package should not go outside directly without itsintensity being attenuated. In other words, the blue light should bekind of “sealed” or “capsulated” so as to prevent blue light leakage tohuman eyes.

In order to make products more competitive in the market, LED packagemanufactures constantly pursue packaging processes which are reliable,low-cost, and high-yield.

SUMMARY OF THE DISCLOSURE

The present disclosure provides a light emitting diode assembly.

The light emitting diode assembly comprises a transparent substrate,comprising first and second surfaces facing to opposite orientationsrespectively; light emitting diode chips, mounted on the first surface;a circuit electrically connecting the light emitting diode chips; atransparent capsule with a phosphor dispersed therein, formed on thefirst surface and substantially enclosing the circuit and the lightemitting diode chips; and first and second electrode plates, formed onthe first or second surface, and electrically connected to the lightemitting diode chips.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present disclosureare described with reference to the following drawings. In the drawings,like reference numerals refer to like parts throughout the variousfigures unless otherwise specified. These drawings are not necessarilydrawn to scale. Likewise, the relative sizes of elements illustrated bythe drawings may differ from the relative sizes depicted.

The disclosure can be more fully understood by the subsequent detaileddescription and examples with references made to the accompanyingdrawings, wherein:

FIG. 1 illustrates an LED assembly according to embodiments of thedisclosure;

FIG. 2A demonstrates a top view of the LED assembly in FIG. 1;

FIG. 2B demonstrates a bottom view of the LED assembly in FIG. 1;

FIG. 3A demonstrates a cross-sectional view of the LED assembly in FIG.2A along line AA, and FIG. 3B demonstrates that along line BB;

FIG. 4 shows a light bulb using several LED assemblies assembled thereinas its lighting sources;

FIG. 5A demonstrates that the LED assembly is fixed on a circuit boardby solder joints;

FIG. 5B demonstrates a clamp with two metal jaws to grasp and hold oneLED assembly vertically on a circuit board;

FIG. 6 illustrates a manufacturing process for producing the LEDassembly of FIGS. 3A and 3B;

FIGS. 7A and 7B demonstrate top and bottom views of an LED assemblyrespectively, according to embodiments of the disclosure;

FIGS. 8A and 8B show two cross-sectional views of the LED assembly inFIG. 7A along line AA and line BB;

FIGS. 8C and 8D show two cross-sectional views of an LED assembly

FIG. 9 exemplifies a manufacturing method to produce an LED assembly;

FIG. 10 is a drawing of LED assembly in one embodiment of thedisclosure;

FIGS. 11A and 11B are top and bottom views of an LED assemblyrespectively;

FIG. 12A demonstrates a cross-sectional view of the LED assembly alongline AA in FIG. 11A;

FIG. 12B demonstrates a cross-sectional view of the LED assembly alongline BB in FIG. 11A;

FIG. 12C shows another LED assembly 400 b;

FIG. 13 is a drawing of an LED assembly in one embodiment of thedisclosure;

FIGS. 14 and 15 are a top view and a cross-sectional view of an LEDassembly, respectively;

FIGS. 16 and 17 are a top view and a cross-sectional view of an LEDassembly, respectively;

FIG. 18 is a cross-sectional view of an LED assembly and FIG. 19demonstrates a method for manufacturing it;

FIG. 20 is a pictorial drawing of an LED assembly;

FIGS. 21A and 21B are a top view and a cross-sectional view of an LEDassembly, respectively;

FIG. 22 demonstrates a cross-sectional view of an LED assembly;

FIG. 23 demonstrates a cross-sectional view of LED assembly;

FIG. 24 is a drawing of an LED assembly;

FIG. 25A shows a top view of the LED assembly;

FIG. 25B shows a top view of the LED assembly;

FIG. 26A is a pictorial drawing of an LED assembly in one embodiment ofthe disclosure;

FIGS. 26B and 26C are a top view and a cross-sectional view of the LEDassembly in FIG. 26A, respectively;

FIG. 27A illustrates an LED lamp using LED assembly as its filament; and

FIG. 27B illustrates an LED lamp using LED assembly as its filament.

DETAILED DESCRIPTION

An LED assembly 100 according to an embodiment of the disclosure isdescribed in detail with reference to FIG. 1. The LED assembly 100 has atransparent substrate 106, which is for example an electricallynon-conductive glass. The transparent substrate 106 has a top surface102 and a bottom surface 104 facing to opposite orientationsrespectively. As shown in FIG. 1, the transparent substrate 106 issubstantially in the form of a thin and longitudinal strip with two ends114 and 116. In this specification, the term, transparent, only meansadmitting the passage of light and could also be referred to astranslucent or semitransparent. Objects situated behind a transparentmaterial in this specification might be distinctly or indistinctly seen.In other embodiments, the transparent substrate 106 is sapphire, ceramicmaterial (ex. Al₂O₃ or AlN), silicon carbide (SiC), or diamond-likecarbon (DLC). It is noted that the transparent substrate 106 can containa plurality of thermal-conduction particles or other components forreducing process temperature during its manufacturing process.

FIG. 2A demonstrates a top view of an LED assembly 100 a, whichexemplifies the LED assembly 100 in one embodiment. Mounted on the topsurface 102 are several blue LED chips 108 electrically connected toeach other through a circuit mainly composed of bonding wires 110, whichprovide interconnection to the blue LED chips 108. Each blue LED chip108 could have only one single LED cell, whose forward voltage is about2 to 3 volts, and this kind of LED chip is referred to as a low-voltageLED chip hereinafter. Comparatively, each blue LED chip 108 mightinclude several LED cells connected in series, and is referred to as ahigh-voltage LED chip hereinafter, because its forward voltage could beas high as 12V, 24V, or 48V, much higher than that of a low-voltage LEDchip. In one embodiment, each LED cell has a light-emitting layer in adiode formed on a substrate, which could be an epitaxial ornon-epitaxial substrate. More specifically, the LED cells in ahigh-voltage LED chip are electrically connected to each other on acommon substrate, not by wire bonding but by some patterned conductivestrips produced by semiconductor processes, such as metallization orlithography that processes all the LED cells at the same time. In FIG. 1and FIG. 2A, the blue LED chips 108 are arranged in two rows beside alongitudinal line that links two ends 114 and 116 of the transparentsubstrate 106. The bonding wires 110 electrically connect the blue LEDchips 108 in series, generating an equivalent LED device with a highforward voltage. The blue LED chips 108 are not limited to connect inseries and arrange in two rows though. In some other embodiments, theblue LED chips 108 might be arranged to any kind of patterns and couldbe electrically connected in series, in parallel, in series-parallel, inbridge or in the combination thereof.

As shown in FIG. 2A, the transparent substrate 106 has a conductive via107 close to the end 114. The conductive via 107 has a via holetunneling through the transparent substrate 106 and the via hole isformed with electrically-conductive material filled therein or coated onits sidewall, so as that the conductive via 107 is capable of couplingor connecting an electric component on the top surface 102 to another onthe bottom surface 104. Nearby the end 114 has a conductive electrodeplate 118 on the top surface 102. The conductive electrode plate 118locates between the end 114 and the conductive via 107. The conductiveelectrode plate 118 does not directly contact with conductive via 107.One of the blue LED chips 108, specifically labeled as 108 a in FIG. 2A,is close to the end 114 and has a bonding wire 110 thereon toelectrically connect to the electrode plate 118. Another blue LED chip108 b, which is close to the end 114, is electrically connected to theconductive via 107 by another bonding wire 110.

All the blue LED chips 108 and all the bonding wires 110 on the topsurface 102 are covered by a transparent body 112 to prevent moisture orchemical in atmosphere from damaging or aging the blue LED chips 108 orthe bonding wires 110. The transparent body 112 is epoxy resin orsilicone, for example. Dispersed in the transparent body 112 is at leastone kind of phosphor that is capable of converting portion of the bluelight from blue LED chips 108 (having a peak wavelength about 430 nm to480 nm) into yellow light (having a peak wavelength from about 570 nm to590 nm) or yellowish green light (having a peak wavelength about 540 nmto 570 nm), such that human eyes perceive white light from the mixture.In one embodiment, the transparent body 112 comprises two kinds ofphosphors dispersed therein. One of the phosphors is capable ofconverting portion of the blue light from blue LED chips 108 into yellowlight or yellowish green light or green (having a peak wavelength fromabout 520 nm to 590 nm) and the other of the phosphors is capable ofconverting portion of the blue light from blue LED chips 108 into redlight (having a peak wavelength from about 610 nm to 680 nm). FIG. 1 isillustrative to show blue LED chips 108 and bonding wires 110 clearlyvisible under transparent body 112. In one embodiment, asaforementioned, the term, transparent, only means admitting the passageof light and could also be referred to as translucent orsemitransparent. Therefore, the transparent body 112 can be translucentor semitransparent such that the LED chips 108 and the bonding wires 110could be distinctly or indistinctly seen behind the transparent body112. In another embodiment, the LED chips 108 and the bonding wires 110could be invisible because of the phosphor dispersed inside thetransparent body 112 and the transparent body 112 appears the color ofthe phosphor dispersed therein.

FIG. 2B demonstrates a bottom view of the LED assembly 100 a. As shownin FIG. 2B, no blue LED chips are mounted on the bottom surface 104.Formed on the bottom surface 104 nearby the end 114 is another electrodeplate 120, which electrically connects to the conductive via 107. In oneembodiment, the electrode plate 120 geometrically overlaps andphysically contacts with the conductive via 107. In another embodiment,the conductive via 107 and the electrode plate 120 do not overlap, and aconductive device, such as a bonding wire or a metal strip, is locatedtherebetween to electrically connect them to each other. FIG. 2B alsoshows an optional electrode plate 122 formed on the bottom surface 104nearby the end 116. This kind of design could have the electrode plates122 and 120 coplanar, and therefore the LED assembly 100 a, duringhandling or transportation, could be steadier to avoid flipping orfalling. The electrode plate 122 electrically floats in this embodiment.In other words, the electrode plate 122 does not electrically couple orconnect to any electric devices or elements in the LED assembly 100 a.When the LED assembly 100 a is laid on a planar surface, the electrodeplate 122 helps stabilize the LED assembly 100 a.

The embodiment shown in FIGS. 2A and 2B has the electrode plates 120 and118 located completely within the top surface 102 or the bottom surface104 as the electrode plates 120 and 118 do not extend across the edgesof the top surface 102 and the bottom surface 104. The electrode plates120 and 118 are not required to be rectangular or to have the same size.For example, one of the electrode plates 120 and 118 could be aboutrectangular, indicating a cathode of the LED assembly 100 a, while theother is about spherical, indicating an anode of the LED assembly 100 a.

In view of electric connection, the blue LED chips 108 and theconductive via 107 are connected in series between the electrode plates120 and 118, which are two power input nodes for powering the LEDassembly 100 a. A conventional power supply (not shown) would have twopower output terminals respectively contacting the electrode plates 120and 118 to drive and illuminate the blue LED chips 108.

FIG. 3A demonstrates a cross-sectional view of the LED assembly 100 a inFIG. 2A along line AA, and FIG. 3B demonstrates that along line BB.

Shown in FIG. 3A, a bonding wire 110 connects the blue LED chip 108 b tothe conductive via 107, which in turn connects to the electrode plate120 on the bottom surface 104. In FIG. 3B, another bonding wire 110connects the blue LED chip 108 a to the electrode plate 118. FIG. 4shows a light bulb using several LED assemblies 100 as its lightingsources. The light bulb in FIG. 4 includes a lamp shell 180, the LEDassemblies 100, a circuit board 192, a heat dissipation apparatus 182and an electrical connection structure 183. The end 114 of each LEDassembly 100 fixes on the circuit board 192, which firmly mounts on theheat dissipation apparatus 182 such that the heat generated by the LEDassembly 100 could be dissipated efficiently. The heat dissipationapparatus 182 stays firmly on the electrical connection structure 183,which is for example an Edison screw base capable of screwing into amatching socket. As both electrode plates 120 and 118 are nearby acommon end 114 of the transparent substrate 106 in one LED assembly 100but locate on opposite surfaces, electrically-conductive blocks, such assolder joints 190, can electrically connect the electrode plates 120 and118 to two different terminals on the circuit board 192, respectively,as shown in FIG. 5A. Beside the electrical connection, the solder joints190 also provide mechanical support to the end 114, to hold the LEDassembly 100 up straight on the circuit board 192, so the LED assembly100, if illuminating, could generate an omnidirectional light field toits surrounding. In FIG. 5A, one LED assembly 100 stands, but is notlimited to stand, almost vertically, only by way of the mechanicalsupport provided by the solder joints 190, which also transmit anynecessary electric power from the circuit board 192 to the LED assembly100. FIG. 5B demonstrates a clamp with two metal jaws 194 to grasp andhold one LED assembly 100 vertically on the circuit board 192. The metaljaws 194 provide both electrical connection and mechanical support toone LED assembly 100, simplifying the manufacture processes required tosecure the LED assembly 100 on the circuit board 192. In someembodiments, an LED assembly 100 stands on the circuit board 192 with asloping position.

Exemplified in FIG. 3A is a vertically-conducting device 130 placed onthe top surface 102 above the conductive via 107. Thevertically-conductive device 130 conducts current vertically, and is byway of examples a PN junction diode (such as a vertical-typelight-emitting diode, a schottky diode or a zener diode), a resistor, orsimply a metal ingot, adhering on the conductive via 107 via aconductive silver paste. In another embodiment, thevertically-conducting device 130 and the conductive silver pastedemonstrated in FIG. 3A could be omitted and a bonding wire 110 bondingon both the conductive via 107 and the blue LED chip 108 b providesnecessary electric connection.

In both non-limiting FIGS. 3A and 3B, each blue LED chip 108 has atransparent adhesive layer 132 thereunder, each adhering only onecorresponding blue LED chip 108 on the top surface 102 of thetransparent substrate 106. In another embodiment, there are severaltransparent adhesive layers 132 on the top surface 102, and at least oneof the adhesive layers carries several blue LED chips 108. In anotherembodiment, there is only one single transparent adhesive layer 132 toadhere all blue LED chips 108 to the top surface 102. Tradeoff occurs tothe area size of one transparent adhesive layer 132. The larger the areaof a transparent adhesive layer 132, the more effective the heatdissipation that the transparent adhesive layer 132 provides to the blueLED chips 108 thereabove, in expense of the more shear stress due to thedifference in thermal expansion coefficients of the transparent adhesivelayer 132 and the transparent substrate 106. Accordingly, the design ofboth the area size of one transparent adhesive layer 132 and the numberof the blue LED chips 132 carried on by one transparent adhesive layer132 depends on actual applications and might vary. In some embodiments,some particles with excellent thermal conductivity, such as aluminapowder, diamond-like carbon, or silicon carbide, whose thermalconductivity is more than 20 W/mK, are dispersed in one transparentadhesive layer 132. These particles help not only dissipate heat, butalso scatter the light from the blue LED chips 108.

The transparent adhesive layers 132 could be epoxy resin or silicone,and mix with phosphor similar with or different from that of thetransparent body 112. The phosphor is, for example, yttrium aluminumgarnet (YAG) or terbium aluminum garnet (TAG). As mentioned, thetransparent body 112 with phosphor covers above and surrounds each blueLED chip 108 while the transparent adhesive layers 132 locates undereach blue LED chips 108. The transparent body 112 and the transparentadhesive layers 132 sandwich blue LED chips 108. In other words, thetransparent body 112 and the transparent adhesive layers 132 together asa whole become a kind of transparent capsule that encloses all blue LEDchips 108, but leaves a portion of electrode plate 118 exposed forexternal electric connection. The blue or UV light from any blue LEDchip 108 inevitably experiences conversion, so that human eyes couldavoid damage or stress caused by over high intensity of the blue or UVlight.

A manufacturing process for producing the LED assembly 100 a of FIGS. 3Aand 3B is described in detail with reference to FIG. 6. In Step 148, atransparent substrate 106 is provided with a conductive via 107 formedin advance. For example, a laser beam could be used to melt a small areaof the transparent substrate 106 so as to form a via hole on thetransparent substrate 106. An electrically-conductive material couldfill in the via hole or be coated on the via hole to form the conductivevia 107. In Step 150, the transparent substrate 106 is pre-cut, formingsome trenches or grooves thereon, which geometrically partition LEDassemblies 100 that are formed and separated in the end. In Step 152,electrode plates 118 and 120 are attached respectively on top and bottomsurfaces (102, 104) of the transparent substrate 106, both nearby theend 114. Incase that an electrode plate 112 is expected, it is formednearby the end 116 in step 152. For example, electrode plates would beformed by screen printing and/or lift-off process, to generate specificconductive patterns on the top and bottom surfaces (102, 104) of thetransparent substrate 106. In Step 154, one or more transparent adhesivelayers 132 with phosphor is formed on the top surface 102 by gluing,printing, spraying, dispensing, or coating, for example.

In Step 155, blue LED chips 108 are mounted on the transparent adhesivelayers 132. A vacuum nuzzle, for example, picks up blue LED chips 108one by one and then put them to adhere onto specific locations of thetransparent adhesive layers 132. In reference to a top view of an LEDassembly, preferably each blue LED chip 108 is completely surrounded bythe periphery of one transparent adhesive layer 132, so as to form aphosphor capsule in the end to totally seal a blue LED chip 108 therein.In other words, the transparent adhesive layer 132 has a flat arealarger than the total area of all blue LED chips 108, so as tocompletely cover the backsides of all blue LED chips 108. Meanwhile, asilver paste can be used to attach a vertically-conductive device 130 onthe top surface 102 and adhere it to the conductive via 107. Bondingwires 110 are formed in step 156, to provide an electric connectionbetween every two blue LED chips 108, between the blue LED chip 108 aand the electrode plate 118, and between the blue LED chip 108 b and thevertically-conductive device 130. In Step 157, a transparent body 112with phosphor is formed on the top surface 102, to encapsulate thebonding wires 110 and the blue LED chips 108, by way of dispensing orscreen printing. In Step 158, a singulation process is performed, wherethe transparent substrate 106 is cut to form a plurality of individualLED assemblies 100, by way of saw cutting along the previously-formedtrenches or grooves for example.

It can be derived from FIG. 6 that, in step 152, the electrode plates120 or 122 are formed on the bottom surface 104. However, in step154-157, all the transparent adhesive layer 132, the LED chips 108, thebonding wires 110 and the transparent body 112 are formed on the topsurface 102. Therefore, only large patterns like the electrode plates120 and 122 are formed on the bottom surface 104, which are immune fromcasual tiny scratches. In addition, holders, carriers, or robot arms fortransporting or holding the transparent substrate 106 could physicallycontact the bottom surface 104 to avoid any damage to the fine patternedstructures on the top surface 102, such that yield improvement isforeseeable.

Embodiments exemplified in FIGS. 3A, 3B, and 6 do not restrain thedirection where the light from a blue LED chip 108 goes. The light froma blue LED chip 108 could go downward through the transparent adhesivelayer 132 and the transparent substrate 106 to provide light thatappears white. The light from a blue LED chip 108 could go upward orvertically through the transparent body 112 to provide white light aswell. Therefore, the LED assembly 100 a is a lighting device that has anomnidirectional white light field. As the lamp in FIG. 4 uses the LEDassemblies 100 as its light resources, it could be an omnidirectionalwhite lighting apparatus, which is possible to replace a traditionalincandescent lamp.

In FIGS. 2A, 2B, 3A and 3B, the blue LED chips 108 mounted directly onthe transparent substrate 106 only through the transparent adhesivelayers 132, but this disclosure is not limited to. FIGS. 7A and 7Bdemonstrate top and bottom views of an LED assembly 100 b respectively,according to one embodiment of the disclosure. Two cross-sectional viewsof the LED assembly 100 b are shown in FIGS. 8A and 8B, and amanufacturing method to produce the LED assembly 100 b is exemplified inFIG. 9. FIGS. 7A, 7B, 8A, 8B and 9 correspond to FIGS. 2A, 2B, 3A, 3B,and 6, where devices, elements or steps with similar or the same symbolsrepresent those with the same or similar functions and could be omittedin the following explanation for brevity.

Different from FIG. 2A, FIG. 7A additionally includes a submount 160positioning inside the periphery of a transparent adhesive layer 132(from the perspective of a top view) and sandwiched between thetransparent adhesive layer 132 and the blue LED chips 108. Submount 160could be glass, sapphire, SiC, or diamond-like carbon. Unlike FIGS. 3Aand 3B, all or a portion of blue LED chips in FIGS. 8A and 8B aremounted on the submount 160, which is adhered onto the transparentsubstrate 106 through the transparent adhesive layer 132.

FIG. 9 uses steps 154 a and 155 a to replace steps 154 and 155 in FIG.6. In Step 154 a, the submount 160 is fixed on the transparent substrate106 using the transparent adhesive layer 132 with phosphor. In oneembodiment, the transparent adhesive layer 132 first adheres to thebackside of the submount 160, followed by attaching the submount 160 onthe transparent substrate 106. In another embodiment, the transparentadhesive layer 132 first adheres to the top surface 102 of thetransparent substrate 106 and the submount 160 is then attached over thetransparent adhesive layer 132. In Step 155 a, the blue LED chips 108are mounted on the submount 160.

The blue LED chips 108 in FIGS. 7A, 7B, 8A, 8B, and 9 could be mountedon the submount 160 using the material the same or similar with that ofthe transparent adhesive layer 132, but the disclosure is not limitedto. Eutectic alloy or transparent glue without phosphor could be used toattach the blue LED chips 108 onto the submount 160. In one embodiment,the top surface of the submount 160 has patterned conductive strips,over which the blue LED chips 108 are mounted by way of flip chiptechnique. As known in the art, flip chip technique, which hassemiconductor chips facing downward on interconnection metal strips forexample, needs no bonding wires shown in step 156 in FIG. 9 might beskipped. Nevertheless, the bonding wires 100 or the silver paste mightbe used in some embodiments for electrically connecting the blue LEDchip 108 b to the conductive via 107, or the blue LED chip 108 a to theelectrode plate 118. In one embodiment, an anisotropic conductivepolymer (ACP) or an anisotropic conductive film (ACF) is used to mountthe blue LED chips 108 on the submount 160.

The LED assembly 100 b in FIGS. 7A, 7B, 8A, 813, and 9 could enjoy thesame advantages as the LED assembly 100 a in FIGS. 2A, 2B, 3A, 313, and6 does. For instance, the solder joints 190 alone can fix the end 114 ofthe LED assembly 100 b onto a printed circuit board and also deliverelectric power from the printed circuit board to the LED assembly 100 b.The bottom surface 104 of the LED assembly 100 b has only large patternsand could be immune from scratch damage, resulting in considerable yieldimprovement. The blue LED chips 108 in the LED assembly 100 b areenclosed by a transparent material with phosphor, so as to prevent bluelight leakage. An omnidirectional lighting apparatus using the LEDassembly 100 b as its lighting sources could replace a conventionalincandescent lamp.

FIGS. 8C and 8D are two cross-sectional views of a LED assembly 100 c,alternatives to FIGS. 8A and 8B respectively. Unlike the LED assembly100 b in FIGS. 8A and 8B, where a single transparent adhesive layer 132mounts the submount 160 on the transparent substrate 106, the LEDassembly 100 c in FIGS. 8C and 8D uses two transparent adhesive layers132 and 133 for mounting the submount 160 on the transparent substrate106, and at least one of the transparent adhesive layers 132 and 133 hasphosphor. In FIGS. 8C and 8D, the transparent adhesive layer 132 hasphosphor, and the transparent adhesive layer 133 does not. Thetransparent adhesive layer 133 could be epoxy resin or silicone. As thetransparent adhesive layer 133 has no phosphor, it could provide betteradhesion to stick on the transparent substrate 106. The transparentadhesive layers 132 and 133 might have the same or different majorsubstance. In one embodiment, another transparent adhesive layer 133could be formed between the submount 160 and the transparent adhesivelayer 132 to improve the adhesion therebetween.

The blue LED chips in FIG. 1 employs bonding wires 110 for electricinterconnection, but the disclosure is not limited to. FIG. 10 is adrawing of a LED assembly 400 in one embodiment of the disclosure, whereblue LED chips 108 are mounted on the top surface 102 using a flip chiptechnique. FIGS. 11A and 11B are top and bottom views of the LEDassembly 400 a respectively, FIG. 12A demonstrates a cross-sectionalview of the LED assembly 400 a along line AA in FIG. 11A, and FIG. 12Bdemonstrates a cross-sectional view of the LED assembly 400 a along lineBB in FIG. 11A. FIGS. 10, 11A, 11B, 12A, and 12B correspond to FIGS. 1,2A, 2B, 3A, and 3B, respectively, where devices or elements with similaror the same symbols refer to those with the same or similar functionsand could be omitted in the following explanation for brevity.

Unlike FIGS. 3A and 3B, which use bonding wires 110 for interconnection,FIGS. 12A and 12B have electrically-conductive strips 402 printed on thetop surface 102 of the transparent substrate 106 and these strips 402connects blue LED chips 108 to each other. As the blue LED chips 108 inFIGS. 12A and 12B have omnidirectional light fields, the LED assembly400 b could be used as a light source for an omnidirectional lightingapparatus. FIG. 12C shows another LED assembly 400 b, which has anadditional phosphor layer 131 coated or attached on the bottom surface104 of the transparent substrate 106. Phosphor layer 131 can convert theblue light from blue LED chips 108 into light with a different color, soas to reduce the possibility of blue light leakage from the bottomsurface 104. In one embodiment, all blue LED chips 108 in the LEDassembly 400 a are replaced by white LED chips, each substantially beinga blue LED chip coated with a phosphor layer, and accordingly blue lightleakage problem might be avoided.

Even though each of the LED assemblies 100 a, 100 b, 100 c, and 400 ahas a conductive via 107, which is a part of a circuit and makes itpossible that the electrode plates 120 and 118 over the top and bottomsurfaces (102 and 104) act as two power input terminals for driving, butthis disclosure is not limited to.

FIG. 13 is a drawing of a LED assembly 200 in one embodiment of thedisclosure. FIGS. 14 and 15 are a top view and a cross-sectional view ofthe LED assembly 200 a, respectively. Different from the LED assemblies100 a and 100 b, which have no electrode plate nearby the end 116 on thetop surface 102, the LED assembly 200 a in FIGS. 14 and 15 has anelectrode plate 119 at the end 116. The electrode plates 118 and 119extend across the ends 114 and 116, respectively. What should be notedis that the LED assembly 200 a has no conductive via 107. The way toproduce the LED assemblies 200 or 200 a in FIGS. 13, 14 and 15 can bederived from the aforementioned teaching and therefore is omitted hereinfor brevity.

In the LED assembly 200 a, the blue LED chips 108 are one-on-one mountedon the transparent adhesive layers 132, but this disclosure is notlimited to. In some other embodiments, some blue LED chips 108 couldshare one of several transparent adhesive layers 132 to mount on thetransparent substrate 106. Alternatively, all blue LED chips 108 mighthave only one single transparent adhesive layers 132 to mount on thetransparent substrate 106 in another embodiment.

FIGS. 16 and 17, similar with FIGS. 14 and 15, are a top view and across-sectional view of the LED assembly 200 b, respectively. FIGS. 16and 17 have nevertheless a submount 160, which carries the blue LEDchips 108 mounted thereabove and fix on to the transparent substrate 106via the transparent adhesive layer 132. Detail of the LED assembly 200 bis omitted herein and could be derived from the teaching in reference tothe LED assembly 100 b in FIGS. 8A and 8B.

FIG. 18 is a cross-sectional view of a LED assembly 200 c and FIG. 19demonstrates a method for manufacturing it. The top view of the LEDassembly 200 c could be similar with FIG. 16, while FIGS. 18 and 19 aresimilar to FIGS. 17 and 9, respectively. Different from FIG. 17, wherethe electrode plates 118 and 119 directly attach on the transparentsubstrate 106, FIG. 18 has the transparent adhesive layer 132 to provideadhesion between the transparent substrate 106 and each of the electrodeplates 118 and 119. In FIG. 19, in step 151, the transparent adhesivelayer 132 forming on the transparent substrate 106 is inserted betweensteps 150 and 152. In other words, formation of the transparent adhesivelayer 132 could be prior to attaching the electrode plates 118 and 119on to the transparent substrate 106. The transparent adhesive layer 132is epoxy resin or silicone, for example, in which phosphor is dispersed.The phosphor in the transparent adhesive layer 132 could be the samewith or similar to that in the transparent body 112. For example, thephosphor is YAG or TAG.

One single transparent adhesive layer 132 is used to mount the submount160 on the transparent substrate 106 in the LED assemblies 200 b and 200c of FIGS. 17 and 18, but this disclosure is not limited to. Alterationcould be introduced to the LED assemblies 200 b and 200 c, to have boththe transparent adhesive layers 132 and 133 (of FIGS. 8C and 8D) betweenthe submount 160 and the transparent substrate 106. In anotherembodiment, the transparent adhesive layer 133 without phosphor could bepositioned between the submount 160 and transparent adhesive layer 132to enhance adhesion therebetween.

The LED assembly 200 a, 200 b, or 200 c has no patterns on the bottomsurface 104, which accordingly does not care any scratches thereon. TheLED assemblies 200 a, 200 b, and 200 c all are suitable foromnidirectional lighting applications and possibly free from blue lightleakage. For instance, a bulb according to an embodiment of thedisclosure can use solder joints or electrically-conductive clamps tofix and power the electrode plates 118 and 119 respectively nearby twoends 114 and 116.

FIG. 20 is a drawing of an LED assembly 300, and FIGS. 21A and 21B are atop view and a cross-sectional view of the LED assembly 300 a,respectively. FIG. 22 demonstrates a cross-sectional view of the LEDassembly 300 a. Formed on the bottom surface 104 of the transparentsubstrate 106 of the LED assembly 300 a are two electrode plates 120 and122, at two ends 114 and 116 respectively. In each of FIGS. 21A, 21B,and 22, the LED assembly 300 a has two conductive vias 107A and 107B,respectively formed somewhere close to two ends 114 and 116. Theelectrode plate 120, as being on the bottom surface 104, uses conductivevia 107A for electrically connecting to one blue LED chip 108 on the topsurface 102, while the electrode plate 122 uses the conductive via 107Bfor electrically connecting to another blue LED chip 108. The blue LEDchips 108 are electrically connected in series between the conductivevias 107A and 107B, or, in other words, between the electrode plates 120and 122. Details of the LED assembly 300 a and possible alternatives orvariations thereto could be derived in reference to other embodimentsdisclosed in this specification and are omitted herein.

FIG. 23 demonstrates a cross-sectional view of an LED assembly 300 b,where the submount 160 is placed under the blue LED chips and above thetransparent adhesive layer 132. Details of the LED assembly 300 b andpossible alternatives or variations thereto could be derived inreference to other embodiments disclosed in this specification and areomitted herein.

The LED assemblies 200 and 300 both have the electrode plates extendingacross the ends 114 and 116, but this disclosure is not limited to. FIG.24 is a drawing of a LED assembly 600. FIG. 25A shows the LED assembly600 a, which could be a top view of the LED assembly 600 and has theelectrode plates 118 and 119, each having an edge aligned with an edgeof the transparent substrate 106. FIG. 25B shows an LED assembly 600 b,which could be another top view of the LED assembly 600 and has theelectrode plates 118 and 119 completely inside the edges of thetransparent substrate 106.

FIG. 26A is a drawing of an LED assembly 700 in one embodiment of thedisclosure. FIG. 26B is a top view of the LED assembly 700. FIG. 26C isa cross-sectional view of the LED assembly 700 along line CC in FIG.26B. The LED assembly 700 in FIGS. 26A and 26B has both electrode plates118 and 123 on the top surface 102 at the end 114, and has nothing onthe bottom surface 104 of the transparent substrate 106. Extending fromthe electrode plates 118 and 123 toward the end 116 are conductivestrips 198 and 196. Blue LED chips 108 are mounted on the top surface102 and between the conductive strips 198 and 196. The cathode and anodeof each blue LED chip 108 are electrically connected to the conductivestrips 198 and 196 with bonding wires 110. Accordingly, the blue LEDchips 108 in FIGS. 26A, 26B and 26C are connected in parallel betweenthe electrode plates 118 and 123, which therefore acts as two powerinput nodes for the LED assembly 700. In one embodiment, the blue LEDchips 108 can be electrically connected to the conductive strips 198 and196 by way of flip chip technique, that is, the blue LED chips 108 areelectrically connected to the conductive strips 198 and 196 withoutusing the bonding wires 110. As shown in FIG. 26C, the blue LED chips108 are substantially encapsulated by the transparent adhesive layer 132and the transparent body 112, both having at least one kind of phosphordispersed therein. In one embodiment, the blue LED chips 108 are totallyenclosed by the transparent adhesive layer 132 and the transparent body112, however, the bonding wires 110 could be still exposed from thetransparent adhesive layer 132 and the transparent body 112. In oneembodiment, the transparent body 112 comprises two kinds of phosphorsdispersed therein. One of the phosphors is capable of converting portionof the blue light (having a peak wavelength about 430 nm to 480 nm) fromblue LED chips 108 into yellow light or yellowish green light or greenlight (having a peak wavelength from about 520 nm to 590 nm) and theother of the phosphors is capable of converting portion of the bluelight from blue LED chips 108 into red light (having a peak wavelengthfrom about 610 nm to 680 nm). The phosphor emitting yellow light oryellowish green light or green light comprises aluminum oxide (such asYAG or TAG), silicate, vanadate, alkaline-earth metal selenide, or metalnitride. The phosphor emitting red light comprises silicate, vanadate,alkaline-earth metal sulfide, metal nitride oxide, a mixture oftungstate and molybdate. The method to produce the LED assembly 700 inFIG. 26A, 26B, or 26C can be derived from the aforementioned teachingand therefore is omitted herein for brevity.

Alteration could be made to the LED assembly 700 in light of thedisclosed embodiments according to the disclosure. For example, the blueLED chips 108 could be mounted on a submount, which adheres to thetransparent substrate 106 via at least one transparent adhesive layerwith or without a phosphor dispersed therein.

FIG. 27A illustrates an LED lamp 500 a using only one LED assembly 300as its filament. The LED lamp 500 a has two clamps 502, and each clamp502 is in a shape of V or Y. In another embodiment, each clamp 502 couldbe substantially rectangular in shape, but has a notch in one of itsedges for fixing the LED assembly 300 thereon. Two jaws of each clamps502 vise one electrode plate at one end of the LED assembly 300, makingthe top surface 102 of the transparent substrate 106 in the LED assembly300 face upward (the direction Z shown in FIG. 27A). Preferably, clamps502 are made of electrically-conductive material, so as to electricallyconnect the electrode plates in the LED assembly 300 to the Edison screwbase of the LED assembly 500 a, which could drain electric power from anEdison socket to power the LED assembly 300. FIG. 27B is similar withFIG. 27A, but the LED lamp 500 b in FIG. 27B uses one LED assembly 600as its filament. Different from the LED lamp 500 a which has the LEDassembly 300 facing upward, the LED assembly 600 in the LED lamp 500 bhas its top surface 102 facing the direction Y, which is vertical to theaxis (Z axis) of the LED lamp 500 b. Any of the assemblies 300 and 600in FIGS. 27A and 27B could be replaced by the LED assembly 200, detailsor alternatives of which could be derived in reference to the teachingdisclosed in this specification and are omitted herein.

The bottom surface 104 of the LED assembly 300 a or 300 b has only theelectrode plates 120 and 122 occupied in a large area, which is immuneto casual scratches, such that yield improvement is expectable. Each ofthe LED assemblies 600 a and 600 b has no pattern on its bottom surface104, and therefore scratches on the bottom surface 104 could not impactthe yield of LED assemblies 600 a and 600 b. Each of the LED assemblies300 a, 300 b, 600 a, and 600 b could be suitable for applications togenerate an omnidirectional light field, and could prevent any bluelight leakage.

The aforementioned embodiments all employ only blue LED chips as theirlighting resource, but this disclosure is not limited to. In someembodiments, some or all blue LED chips are replaced with red or greenLED chips, for example.

Because of the transparency provided by the transparent substrate 106and the transparent adhesive layer 132, the LED assemblies in someembodiments could have an omnidirectional light field and be suitablefor applications to generate an omnidirectional light field. The blueLED chips 108 in some embodiments are substantially encapsulated by thetransparent adhesive layer 132 and transparent body 112 with phosphor,to avoid blue light leakage. One embodiment of the disclosure has a LEDassembly with only one end fixed on a circuit board to provide bothelectric power and mechanic support. Nevertheless, a LED assembly ofanother embodiment has two ends, both fixed for mechanic support andcoupled for receiving electric power from a power source. An LEDassembly according to some embodiments has no fine patterns on itsbottom surface, immune to scratch damage and convenient for the LEDassembly transportation.

While the disclosure has been described by way of example and in termsof preferred embodiment, it is to be understood that the disclosure isnot limited thereto. To the contrary, it is intended to cover variousmodifications and similar arrangements (as would be apparent to thoseskilled in the art). Therefore, the scope of the appended claims shouldbe accorded the broadest interpretation so as to encompass all suchmodifications and similar arrangements.

What is claimed is:
 1. A light emitting diode assembly, comprising: atransparent substrate, comprising first and second surfaces facing toopposite orientations respectively; light emitting diode chips, mountedon the first surface; a circuit electrically connecting the lightemitting diode chips; a transparent capsule with a phosphor dispersedtherein, formed on the first surface and substantially enclosing thecircuit and the light emitting diode chips; and first and secondelectrode plates, formed on the first or second surface, andelectrically connected to the light emitting diode chips.
 2. The lightemitting diode assembly as claimed in claim 1, wherein the transparentcapsule comprises a transparent adhesive layer having a first phosphordispersed therein, and placed between at least one of the light emittingdiode chips and the transparent substrate.
 3. The light emitting diodeassembly as claimed in claim 2, wherein the transparent capsulecomprises transparent adhesive layers, and the light emitting diodechips are mounted one-on-one on the transparent adhesive layers.
 4. Thelight emitting diode assembly as claimed in claim 2, wherein thetransparent capsule has a single transparent adhesive layer, and all thelight emitting diode chips in the light emitting diode assembly aremounted on the transparent adhesive layer.
 5. The light emitting diodeassembly as claimed in claim 2, wherein the transparent capsule has atransparent body covering on and surrounding the light emitting diodechips, and the transparent body has a second phosphor dispersed therein.6. The light emitting diode assembly as claimed in claim 2, furthercomprising a submount placed under the light emitting diodes and on thetransparent adhesive layer.
 7. The light emitting diode assembly asclaimed in claim 6, wherein the light emitting diode chips are mountedon the submount by way of flip chip technique.
 8. The light emittingdiode assembly as claimed in claim 1, wherein the circuit comprises abonding wire electrically connecting two of the light emitting diodes.9. The light emitting diode assembly as claimed in claim 1, wherein thetransparent substrate is substantially in the form of a longitudinalstrip having two opposite ends, and the first and second electrodeplates are placed on the first and second surfaces respectively andnearby one common end of the two opposite ends.
 10. The light emittingdiode assembly as claimed in claim 1, wherein the transparent substrateis substantially in the form of a longitudinal strip having two oppositeends, and the first and second electrode plates are placed nearby thetwo opposite ends respectively.
 11. A method for manufacturing a LEDassembly, comprising: providing a transparent substrate, having firstand second surfaces facing the opposite orientations; mounting LED chipson the first surface using at least one transparent adhesive layer,wherein the transparent adhesive layer has a phosphor dispersed therein;forming a circuit one the first surface for interconnection between theLED chips; and forming a transparent body covering on and surroundingthe LED chips, wherein the transparent body has a first phosphordispersed therein.
 12. The method as claimed in claim 11, whereincomprising: mounting the LED chips on the first surface using twotransparent adhesive layers; wherein at least one of the two transparentadhesive layers has a second phosphor, the other has no phosphor, andthe two transparent adhesive layers stack between one of the LED chipsand the transparent substrate.
 13. The method as claimed in claim 11,further comprising: mounting the LED chips on a submount; and mountingthe submount on the first surface of the transparent substrate.
 14. Themethod as claimed in claim 13, comprising: forming the at least onetransparent adhesive layer on a backside of the submount; and fixingboth the submount and the transparent adhesive layer on the firstsurface.
 15. The method as claimed in claim 13, wherein the LED chipsare mounted on the submount by way of flip chip technique.
 16. Themethod as claimed in claim 11, wherein the transparent substratecomprises a via hole tunneling therethrough and the via hole is formedwith conductive material therein to provide a conductive via, the methodcomprising: forming a first electrode plate on the first surface; andforming a second electrode plate on the second surface, wherein thesecond electrode plate contacts the conductive via; wherein the LEDchips and the conductive via are connected in series between the firstand second electrode plate.
 17. The method as claimed in claim 11,wherein the transparent substrate is substantially in the form of alongitudinal strip having two opposite ends, and the method furthercomprises forming first and second electrode plates on the first andsecond surfaces respectively and nearby one common end of the twoopposite ends.
 18. The method as claimed in claim 11, wherein thetransparent substrate is substantially in the form of a longitudinalstrip having two opposite ends, and the method further comprises formingfirst and second electrode plates nearby the two opposite endsrespectively and on the first surface.
 19. The method as claimed inclaim 11, wherein the transparent substrate is substantially in the formof a longitudinal strip having two opposite ends, and the method furthercomprises forming first and second electrode plates nearby the twoopposite ends respectively and on the second surface.
 20. The method asclaimed in claim 11, wherein the transparent substrate is substantiallyin the form of a longitudinal strip having two opposite ends, and themethod further comprises forming first and second electrode plates onthe first surface and nearby one common end of the two opposite ends.